Chrome only supports native WebVR on Android today. You must be using a
Daydream headset with a Pixel phone.

The WebVR Polyfill may not
always be a 1:1 match with native implementations of the spec. If you plan
to use the Polyfill, be sure to check on both VR-capable and non-VR devices.

Users must click a VR controller button before it's available to your
code. You must account for this in your code, typically by showing the user
a message requesting they press a controller button at the start of their VR
experience.

You must enable Gamepad pose information in Chrome 56 when running locally.
The gamepad information will not contain pose (or location) information when
running on localhost unless you enable the Gamepad Extensions runtime flag in
Chrome 56. If you are running an Origin Trial the Gamepad Extensions are
enabled with the WebVR API.